Quite honestly, it was way too easy the back half of Wrath and the last tier of Cataclysm to keep alts around.

I'd go further, the ease of gearing and maintaining a raid ready alt was threatening to create problems in the broader raiding metagame.

When guilds were working on 0% HLK there was a running joke on these forums and others that the first HLK kill would be the first guild to recruit 18 warlocks. Alts have the potential to turn that joke into reality. Right now maintaining a fleet of alts is mostly in those world and region first quality guilds however the ease and advantage of maintaining a fleet of alts was such that it was beginning to trickle down into lower level guilds. At a certain point Blizzard would have to start making balancing assumptions based on guilds being able to field 8 of a class at a moment's notice and then alts would become a requirement for all guilds concerned about progression.

With MoP Blizzard is trying to head off the trend before it gets to that point, you can still maintain a fleet of alts but its a lot more time consuming to hopefully keep it confined to the upper crust of raiding.

At a certain point Blizzard would have to start making balancing assumptions based on guilds being able to field 8 of a class at a moment's notice and then alts would become a requirement for all guilds concerned about progression.

That time has come and gone already.

Weren't you around for Dragon "We didn't realize guilds had 13 Dragonwraths" Soul?

What you fail to recognize is that some people simply like playing alts. That would be me and I don't raid. Casuals aren't the ones that get burnt out on content when they don't even raid. It's the raiders.

I like playing alts too. Doesn't mean alts need to be able to get within a few item levels of my main with a couple weeks' work.